1. Field of the Invention
The present invention relates to a process for producing acrylonitrile from propylene, or methacrylonitrile from isobutylene, by ammoxidation. More particularly, the present invention is concerned with a process for producing acrylonitrile or methacrylonitrile by reacting propylene with, or reacting isobutylene with ammonia and molecular oxygen in-the gaseous phase in the presence of an improved ammoxidation catalyst composition comprising a novel oxide catalyst and a silica carrier having the oxide catalyst supported thereon, the oxide catalyst comprising, in specific ratios, oxides of molybdenum, bismuth, iron, nickel, a mixture of chromium and indium, at least one element selected from potassium, rubidium and cesium and optionally at least one element selected from manganese, magnesium, zinc, cerium, sodium, and phosphorous.
2. Discussion of Prior Art
There has been well known a process for producing acrylonitrile from propylene, or methacrylonitrile from isobutylene, by ammoxidation in the gaseous phase, which comprises reacting propylene with, or reacting isobutylene with ammonia and molecular oxygen. This process, which has been widely known as an ammoxidation process, has been practiced on a commercial scale. With respect to catalysts for use in this ammoxidation process, a number of proposals have been made, wherein the catalysts have compositions containing molybdenum, bismuth and iron as essential components.
For example, in Unexamined Japanese Patent Application Laid-Open Specification No. 2-59046, U.S. Pat. No. 5,071,814, Examined Japanese Patent Application Publication No. 40-2532, GB Patent No. 1,434,581, Examined Japanese Patent Application Publication No. 51-6649, GB Patent No. 1,436,475, U.S. Pat. No. 4,190,556, U.S. Pat. No. 4,162,234, U.S. Pat. No. 4,167,494 and U.S. Pat. No. 5,093,299, the so-called multi-component oxide catalysts containing molybdenum, bismuth and iron are disclosed.
The catalysts disclosed in the above-mentioned patent documents have shown various advantageous characteristics. But, in the ammoxidation using these catalysts, the occurrence of side reactions is not effectively suppressed, so that the yield of acrylonitrile or methacrylonitrile is not satisfactorily high.